1. Field of the Invention
The present invention generally relates to substrate processing systems. More specifically, the present invention relates to a method for performing an etch process in a substrate processing system.
2. Description of the Related Art
Manufacturing of optical and opto-electronic devices typically comprises a number of processes having limited analogies to the fabrication of electronic integrated circuits on semiconductor substrates. Such processes may comprise forming a structure having a smallest width of about 1 to 20 μm and a high aspect ratio of about 5 to 50 (e.g., trench, via, and the like), as well as fabrication of a structure having the aspect ratio less than 5 (e.g., isolated line, arrayed waveguide, and the like). Herein the term “aspect ratio” refers to a height of the structure divided by its smallest width. Such structures are generally formed in an oxide or oxynitride dielectric layer, e.g., a layer of silicon dioxide (SiO2), silicon oxynitride (SiNXOY, where x and y are integers), and the like.
These high aspect ratio structures are generally fabricated in the dielectric layer using a one-step etch process. However, such one-step etch processes typically have a low etch selectively between the material of the etch mask and the dielectric material being etched so that formation of the high aspect ratio structures are difficult to achieve. Additionally, polymer by-products from the etch process may accumulate on sidewalls of the structures during the etch process, producing structures having undesirable tapered profiles.
Therefore, there is a need in the art for a method of etching a structure in a dielectric material on a substrate during fabrication of optical, opto-electronic, and other devices.